Hi All,
There's currently a couple of bugs in FixedSizeBuffer. The current code
can't correctly ascertain the size of the buffer so it allows one to
fill it indefinitely overwriting occupied cells. It also creates a
buffer array 1 element too big (combined with the previous
problem allowing the buffer to hold in memory one object too many).
Attached is a patch to fix both problems.
Cheers,
Marcus
BTW - is FixedSizeBuffer allowed to hold null elements, as this
case seems to be broken as well ? (remove() won't remove null
items, but add() will store them).
--
.....
,,$$$$$$$$$, Marcus Crafter
;$' '$$$$: Computer Systems Engineer
$: $$$$: ManageSoft GmbH
$ o_)$$$: 82-84 Mainzer Landstrasse
;$, _/\ &&:' 60327 Frankfurt Germany
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&&&&&&&:
Index: FixedSizeBuffer.java
===================================================================
RCS file:
/home/cvspublic/jakarta-avalon-excalibur/src/java/org/apache/avalon/excalibur/collections/FixedSizeBuffer.java,v
retrieving revision 1.1
diff -u -r1.1 FixedSizeBuffer.java
--- FixedSizeBuffer.java 20 Dec 2001 18:28:33 -0000 1.1
+++ FixedSizeBuffer.java 25 Feb 2002 17:42:52 -0000
@@ -18,10 +18,11 @@
private final Object[] m_elements;
private int m_start = 0;
private int m_end = 0;
+ private boolean m_full = false;
public FixedSizeBuffer( int size )
{
- m_elements = new Object[ size + 1 ];
+ m_elements = new Object[ size ];
}
public FixedSizeBuffer()
@@ -37,7 +38,11 @@
{
size = m_elements.length - m_start + m_end;
}
- else
+ else if ( m_end == m_start )
+ {
+ size = ( m_full ? m_elements.length : 0 );
+ }
+ else
{
size = m_end - m_start;
}
@@ -52,19 +57,23 @@
public final void add( Object element )
{
- if ( size() > m_elements.length )
+ if ( m_full )
{
throw new BufferOverflowException( "The buffer cannot hold more than "
+ m_elements.length + " objects." );
}
- m_elements[ m_end ] = element;
+ m_elements[ m_end++ ] = element;
- m_end++;
if ( m_end >= m_elements.length )
{
m_end = 0;
}
+
+ if ( m_end == m_start )
+ {
+ m_full = true;
+ }
}
public final Object remove()
@@ -78,15 +87,16 @@
if ( null != element )
{
- m_elements[ m_start ] = null;
+ m_elements[ m_start++ ] = null;
- m_start++;
if ( m_start >= m_elements.length )
{
m_start = 0;
}
+
+ m_full = false;
}
return element;
}
-}
\ No newline at end of file
+}
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